1. Field of the Invention
The present invention relates to a solid-state imaging device such as a complementary metal oxide semiconductor (CMOS) image sensor and a camera system.
2. Description of the Related Art
As such a solid-state imaging device (image sensor), a charge coupled device (CCD), the CMOS, and the like are widely used in practice.
In general, with the solid-state imaging device such as the CCD and the CMOS image sensor, an analog signal obtained by a photoelectric conversion element was converted into digital data to be recorded using an analog-to-digital (AD) converter separate from the solid-state imaging device.
Presently, to increase the processing speed and to reduce the size, the solid-state imaging device and the AD converter are integrated in one chip or one package.
As solid-state imaging devices that operate at high speed, various devices are proposed (see, for example, Japanese Unexamined Patent Application Publication Nos. 2006-340044, 2006-80861, and 2003-234967).
The solid-state imaging device disclosed in Japanese Unexamined Patent Application Publication No. 2006-340044 not only integrates one or more AD converters but also integrates thousands of AD converters in a column parallel manner, resulting in high speed.
The solid-state imaging device disclosed in Japanese Unexamined Patent Application Publication No. 2006-80861 includes a column parallel sample and hold circuit, in which a plurality of columns share a pipelined AD converter, resulting in high speed.
The solid-state imaging device disclosed in Japanese Unexamined Patent Application Publication No. 2003-234967 also includes the column parallel sample and hold circuit and uses the pipelined AD converter, like the technology disclosed in Japanese Unexamined Patent Application Publication No. 2006-80861 described above.